The present invention generally relates to a mobile weapon system, and more particularly to a mobile weapon system including an electrically operated gun and an energy supply arrangement wherein energy can be stored in a storage unit and can be supplied to the gun as electric energy when required for firing or shooting.
Previously used ballistic weapons have been based on the principle that a missile located in a gun barrel is accelerated by an explosion-like propellant combustion. Such gas pressure weapons have the disadvantage that the muzzle velocity cannot be increased to above approximately 1,800 m/sec for physical reasons because the maximum achievable muzzle velocity is limited by the highest possible gas expansion rate. Thus, gas pressure weapons generallY have the disadvantage of relatively long missile flying times, which has a negative effect, despite the availability of precise target acquisition systems, particularly when fighting remote, fast-moving targets, such as airplanes and helicopters.
From German patents (DE-PS) 139 768 and 376 391, weapons have become known, in which the missile acceleration takes place by means of the Lorenz force, therefore electrically. Guns of this type are not bound by any practical limits with respect to their muzzle velocity, and muzzle velocities of more than 10,000 m/sec. have already been reached.
However, it is a problem in the case of electric weapons of this type that for a very short time period (order of 1 msec), extremely high power must be available for the acceleration of the missile. The required power is in the range of gigawatts, and the energy to be supplied to the missile is in the range of megajoules, if missiles of a significant mass, for example, several kilograms, are to be accelerated. In this case, for reasons of air resistance, muzzle velocities of up to 4,000 m/sec. are sensible.
In order to store such large amounts of energy, a static electric storage device is contemplated, for example, in the form of a capacitor charged by a generator. As an alternative, kinetic energy storage devices have been known, in which energy is stored in the form of rotational energy, in a centrifugal mass coupled with a generator. When the centrifugal mass is braked, the energy can be drawn as electric energy at the generator winding, and, for example, by an inductive intermediate storage device, can be supplied to the electric weapon for the forming of pulses.
Although, with the latter method, the required energy can be made available within a foreseeable time period, the problem exists that the requirement of firing a number of shots within a short sequence cannot be met, since up to now, no possibilities have existed for a fast storage device regeneration. With conventional power engines which, if they have an acceptable weight and size, generate a power of up to one megawatt, the "recharging" after each shot would take so long that either a shot could be fired only approximately every minute, or enormous storage systems would be required for the storage of energy for a large number of shots. While the former possibility would be unacceptable for reasons of military tactics, the latter possibility would enlarge the required storage space or the storage mass to such an extent that it could not be implemented even in the case of battle tanks.
It is, therefore, an object of the present invention to provide a weapon system which utilizes electrical energy to accelerate a projectile and which is capable of firing a fast sequence of shots while, in each case, only that energy is to be stored that is required for one or a few shots.
It is yet another object of the present invention to generate the required energy for operating the weapon system within a very short time period which is in the range of a few seconds.
According to the invention, these and other objects are achieved by a special adaptation of a turbine arrangement which is provided to charge an energy storage unit for supplying energy to the gun of the mobile weapon system.
Important advantages of the weapon system according to the invention include that, for a very short time, which amounts to approximately two to four seconds, a very high power can be achieved, whereby, during this time, the storage unit can be charged to energies in the range of approximately 50MJ, and thus missiles of considerable mass can be fired after this charging time. This feature makes it possible to limit the storage requirement to the amount of energy of one or a few shots (battle tank cannon), without the occurrence of unacceptable charging times. This feature further makes it also possible to reduce the storage unit size to such an extent that it can be housed in a combat vehicle. In addition, the energy supply unit according to the invention itself requires little space and is of an only negligible weight when compared with the required fuel, driving and storage masses.
By means of the combination of characteristics according to the invention, the power of the turbine can advantageously be increased for a short time to values higher than 15 MW, so that such short charging times can be achieved. Advantageously, in this case, the turbine entry temperature is increased considerably above the permissible component temperatures, which, however, in view of the short full load periods and the thermal conductivity delay to the component core, does not lead to a destruction of components.
In an advantageous further feature of preferred embodiments of the present invention, the storage unit is constructed as a kinetic storage device which has a centrifugal mass and a generator winding, in which case, when required (shot), rotational energy which is stored in the centrifugal mass by an outside wiring of the generator winding can be transmitted as electric energy. This feature has the advantage that the turbine is taken up to full load for a short time in order to achieve combat readiness, whereby the centrifugal mass is driven up to nominal speed. Subsequently, the turbine may be controlled down to idling speed or to a stop, in which case the energy remains stored in the centrifugal mass, and combat readiness is therefore maintained. With the firing of a shot, the centrifugal mass is decelerated from its nominal speed to a lower rotational speed, which preferably corresponds to approximately the idling speed of the turbine. As the result of the brief full load of the turbine, the centrifugal mass, again within two to four seconds, can be brought to the nominal speed, and thus be made ready for another shot.
In another advantageous further feature of preferred embodiments of the present invention, an overrunning clutch is provided between the turbine shaft and the storage unit, this overrunning clutch being disengaged when the turbine speed is lower than the storage device speed. As a result, it is achieved in a simple manner that the storage device speed is maintained when the turbine speed is reduced, and the turbine drives the storage device to nominal speed during the running-up. Advantageously, the combustion chamber of the turbine is acted upon by a self-igniting combination of liquid fuel and liquid oxydant, whereby the conditions required for the operation of the turbine can be achieved with a short delay.
In an alternative embodiment of the invention, the combustion chamber can be ignited by a self-igniting fuel oxidant mixture and subsequently can be converted to kerosene (Diesel oil) as the fuel. As a result, with a fast ignition, the amount of the required special fuel is reduced, which has a particularly advantageous effect when it is used in connection with a vehicle driving system burning kerosene or Diesel oil.
According to yet another advantageous further feature of preferred embodiments of the present invention, the turbine is constructed in two parts. The combustion chamber is arranged between the turbine parts, which operationally are connected in parallel, in such a manner that the fuel gas flow generated in the combustion chamber is deflected into two partial flows directed in opposite directions, which act upon the turbine parts. As a result, a compact construction can be achieved which requires little space and in which case, at the same time, the gas forces of the turbine parts directed in an axial direction of the shaft cancel one another, and as a result, relieve the shaft bearing of the turbine shaft of unwanted wear and stress.
The turbine parts are preferably constructed in five stages respectively, whereby a thermodynamically advantageous conversion of energy can be achieved in the turbine.
According to still another advantageous further feature of preferred embodiments of the present invention, the combustion chamber is constructed as a single-tube combustion chamber and is connected with the turbine by a ring duct. This permits a simple, rugged construction that can be serviced easily.
Advantageously, water may also be injected into the combustion chamber for use as ballast, As a result, the gas volume can advantageously be increased to the permissible extent while the gas temperatures are reduced at the same time.
A preferred feature of certain embodiments of the present invention also provides that the injection of fuel, oxidant and water takes place by utilizing pumps which are constructed as controllable displacement pumps and can be driven by one or several hydraulic or electric motors. As a result, high combustion chamber pressures can be achieved with short run-up times.
A further feature of preferred embodiments of the present invention provides that the combustion chamber, the ring duct, the blading of the first or of the first two turbine stage(s) as well as the walls acted upon by the hot gas, are lined on the inside with heat-resistant insulating layers. The heat capacity of the insulating layers is chosen to be such that the maximally permissible component temperatures, at significantly higher combustion chamber temperatures, will not be reached until after a plurality of charging cycles, i.e., a time longer than approximately 15 seconds. This has the advantage that a plurality of shots can be fired in short succession, the turbine during this time running at full load. For example, in the case of a succession of five shots, the turbine will run at full load for approximately 15 seconds and subsequently will run down.
Another advantage is the fact that the rotating turbine parts, particularly, for example, the turbine shaft and the blading, in this case, also operate as energy storage devices. As a result of the heat capacities of the insulating layers, it is prevented in this case that, during this time, the component temperatures become too high.
In an advantageous further feature of preferred embodiments of the present invention, the rotor blades of the first or of the first two turbine stage(s) can be cooled by water from the provided ballast quantity, which can be supplied, for example, through the free end of the turbine shaft and discharged from the rotor blades at their trailing profile edges. This advantageously permits a simultaneous effective cooling of the rotor blades and the admixing of part of the water ballast.
Likewise, the guide blades of the first or the first two turbine stage(s) can be cooled by water from the provided ballast quantity, in which case the water can be supplied, for example, through the turbine housing and discharged from the guide blades at their trailing profile edges. As a result, the above-mentioned advantages can also be achieved for the guide blades of the turbine.
In an advantageous further feature of preferred embodiments of the present invention, the weapon system is housed in a combat vehicle which is driven by a separate vehicle driving system. This makes it possible that the high driving power required in the operation of the vehicle and the energy supply to the electric weapon can be achieved simultaneously.
Preferably, exhaust gas from the vehicle driving system can be supplied to the combustion chamber through a blockable gas line, in which case the turbine can be maintained at an idling speed. As a result, the exhaust gas of the vehicle driving system can advantageously be used for maintaining the turbine at such a rotational speed which permits a fast running-up to full load. The idling speed is approximately in the range of 80% of the full load speed, for the purpose of which a power in the range of 0.10% of the power at full load is required.
Advantageously, the vehicle driving system has an internal-combustion-engine-driven driving generator, which, by means of a control element, feeds one or several driving motors, the static electric storage device being selectively chargeable from the driving engine by a change-over switch. As a result, an increased redundancy of the weapon system is made possible, particularly during a failure of the turbine sYstem. Although, in this case, the time required for the charging of the storage unit would be much longer, a limited operatability of the combat vehicle is maintained. As an alternative, when the vehicle driving system fails, the energy stored in the storage unit or the power available in the charging assembly, with a corresponding adaptation, can be used for driving the driving motors, thereby ensuring a mobility of the damaged vehicle over a moderately short path.
In an alternative embodiment of the present invention, the generator winding of the storage unit, which is wired as a motor, can be acted upon by the driving generator of the vehicle driving system in order to accelerate the centrifugal mass. By means of this reversed wiring of the generator winding, a redundancy, i.e., a limited operability of the electric weapon, is also maintained when the turbine fails.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.